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    <meta charset="UTF-8">
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    <title>Document</title>
</head>
<body>
    <script>
        // Array.prototype.myEvery = function ( fn ) {
        //     var flag ; 
        //     for( var i = 0 ; i < this.length ; i ++ ) {
        //         var res = fn( this[i] , i , this ) ; 
        //         if ( !res ) {
        //             flag = false ;
        //             break ; 
        //         } else {
        //             flag = true ;
        //         }
        //     } 
        //     return flag ;
        // }
        Array.prototype.myFilter = function ( fn ) {
            var newArr = new Array();
            for ( var i = 0 ; i < this.length ; i ++ ) {
                var res = fn( this[i] , i , arr );
                if ( res ){
                    newArr.push(this[i]);
                }
            }
            return newArr ; 
        }
        var arr = [1,2,3,4,1] 
        var res = arr.myFilter( function ( item , key , arr ){
            return key>=1;
        });
        console.log(res);

        var res = arr.filter(function ( item , key , arr ){
            return arr ;
        });
        console.log(res);
    </script>
</body>
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